DMP 440 (260-2808) Buffer Faxback Doc. # 4451 Buffer size- Approximately 6K The DMP-440's ability to temporarily store data is one of its main advant- ages over a typewriter. Codes sent to a typewriter (that is, keys you press) are transferred immediately to the paper. Codes sent to a printer are not printed immediately; they are stored in a separate section of memory in the printer called the buffer. When the buf- fer fills or certain codes are received (that is, LF or CR), the buffer is emptied and all data is printed on the paper. What happens after the buf- fer data prints depends on the circumstances. In some cases, printing con- tinues on the same line; in others, the print head moves to a different position relative to the paper. In the DP mode, commands for changing fonts, line feed, and so on, can be stored in the printer buffer until data is printed. TIPS ON THE DMP 440 BUFFER... FOR DP, WP, AND GRAPHICS MODES: * The buffer allocates a fixed number of dots, depending on the character width selected. The buffer empties when the data stored equals that number. Printing resumes at the start of the next line. * The last character received by the buffer is printed at the start of the next line following an automatic line feed and carriage return. * The form feed code (FF = 12 decimal) automatically activates printing (if the code is received by the DMP 440). If you select "LF only" (DIP switch 1-3), the buffer prints and the print head moves to the next top-of-form line without a carriage return. Other- wise, the printing position is set at the start of the next top-of-form line. * The carriage return code (CR = 13 decimal) automatically activates printing (assuming that at least one character code is already in the buffer). If you Select "carriage return only" (DIP switch 1-2), the printing position moves to the start of the current line, and the next buffer full prints subsequent characters over the current line. Other- wise, subsequent characters print at the start of the next line. * The line feed code (LF = 10) automatically activates printing. If you select "LF only" (DIP switch 1-3), the buffer prints and the print head moves to the next print line without a carriage return. Otherwise, the printing position is set at the start of the next print line. * If the computer delays more than a second before sending the next print code, the buffer prints. Printing continues from the current position. * The dot positioning sequence (27 16 n1 n2) prints the buffer if the designated position is to the left of the current position. Printing continues in the current line at the dot address specified by the (27 16) command. DATA AND WORD PROCESSING MODES ONLY: * The backspace command activates printing. Printing continues in the cur- rent line at the dot address specified by the command. * If you select a character set of different dot density, the data in the buffer prints. Codes for changing character sets are: 27 17, 27 18, 27 19, 27 20, 27 23, 27 29, 27 31, 27 32. Printing continues in the current line with the new character style. * When the printer receives the start graphics mode (18) followed by stand- ard characters, the buffer prints. Dot graphics printing continues form the current character position. GRAPHICS MODE ONLY: * When the printer receives the end graphics code and returns to a stand- ard or condensed character printing condition, the buffer prints. The DMP-440 returns to the previous print mode, and printing continues in the same line from the current print position. NOTES: * In the description, "next line" means the new line reached by perform- ing a line feed operation. In data processing mode, if a reverse line feed is set in the memory, the line feed operation causes paper to move in the reverse direction. * Repeat data can cause a buffer full or overflow condition. The overflow characters are wrapped around and printed at the beginning of the next line. (abo-07/26/93)